Products containing the analgesic acetaminophen and the sleep aid diphenhydramine hydrochloride have been marketed for a number of years. Such products are marketed in various final solid dosage forms including tablets, caplets and gelcaps. The process used to produce solid dosage forms which are then formed into a final solid dosage form generally comprises a single granulation process wherein acetaminophen and diphenhydramine hydrochloride together with certain excipients are dry blended and then granulated by spraying the dry blended material with a suitable binder such as starch while the dry blend is mixed in a granulator such as a Fielder granulator. The granulation so formed is then dried, milled and formed into one of a number of solid dosage forms by conventional processing. As used herein the term "solid dosage form" means the solid core component of a dosage form, which may then be processed into a final solid dosage form. In the case of a caplet, it is the core caplet without any coating. In the case of a gelcap, it is the core caplet without any precoat or gelatin coating. In the case of a tablet, it is the core tablet without any coating. Generally, the solid dosage form is the core component formed from a conventional compressing step of the granulation before it undergoes any further processing. The term "final solid dosage" form means a solid dosage form, which has undergone further processing, such as precoating, coating, gelatin coating, printing or the like.
The acetaminophen/diphenhydramine hydrochloride solid dosage forms produced by this process possess inadequate hardness, generally about 7 kp or less. As a result, the solid dosage forms may become damaged during processing and packaging. This creates quality control problems and increases production costs. Another problem with this process is that the solid dosage forms produced possess a relatively high friability of greater than 1.0%.
Accordingly, it is an object of the present invention to develop a process which produces a medicament which when made into a solid dosage form has an adequate hardness of greater than 7 kp and preferably of from about 9-12 kp and a friability of less than about 1%.